title: A prospective study of the factors affecting outcomes of nonsurgical root canal treatment: part 1: periapical health.
abstract: OBJECTIVE
  To investigate the probability of and factors influencing periapical status of teeth following primary (1°RCTx) or secondary (2°RCTx) root canal treatment.
  
  
  METHODS
  This prospective study involved annual clinical and radiographic follow-up of 1°RCTx (1170 roots, 702 teeth and 534 patients) or 2°RCTx (1314 roots, 750 teeth and 559 patients) carried out by Endodontic postgraduate students for 2-4 (50%) years. Pre-, intra- and postoperative data were collected prospectively on customized forms. The proportion of roots with complete periapical healing was estimated, and prognostic factors were investigated using multiple logistic regression models. Clustering effects within patients were adjusted in all models using robust standard error.
  
  
  RESULTS
  proportion of roots with complete periapical healing after 1°RCTx (83%; 95% CI: 81%, 85%) or 2°RCTx (80%; 95% CI: 78%, 82%) were similar. Eleven prognostic factors were identified. The conditions that were found to improve periapical healing significantly were: the preoperative absence of a periapical lesion (P = 0.003); in presence of a periapical lesion, the smaller its size (P ≤ 0.001), the better the treatment prognosis; the absence of a preoperative sinus tract (P = 0.001); achievement of patency at the canal terminus (P = 0.001); extension of canal cleaning as close as possible to its apical terminus (P = 0.001); the use of ethylene-diamine-tetra-acetic acid (EDTA) solution as a penultimate wash followed by final rinse with NaOCl solution in 2°RCTx cases (P = 0.002); abstaining from using 2% chlorexidine as an adjunct irrigant to NaOCl solution (P = 0.01); absence of tooth/root perforation (P = 0.06); absence of interappointment flare-up (pain or swelling) (P =0.002); absence of root-filling extrusion (P ≤ 0.001); and presence of a satisfactory coronal restoration (P ≤ 0.001).
  
  
  CONCLUSIONS
  Success based on periapical health associated with roots following 1°RCTx (83%) or 2°RCTx (80%) was similar, with 10 factors having a common effect on both, whilst the 11th factor 'EDTA as an additional irrigant' had different effects on the two treatments.
authors.affiliation: Unit of Endodontology, UCL Eastman Dental Institute, University College London, London, UK. p.ng@eastman.ucl.ac.uk
authors.forename: Y-L
authors.initials: YL
authors.lastname: Ng
authors.forename: V
authors.initials: V
authors.lastname: Mann
authors.forename: K
authors.initials: K
authors.lastname: Gulabivala
mesh_terms: D000328:Adult; D002614:Chelating Agents / Q000627:therapeutic use; D002710:Chlorhexidine; D015331:Cohort Studies; D000075202:Contraindications; D003751:Dental Fistula / Q000473:pathology; D003786:Dental Pulp Cavity / Q000293:injuries / Q000473:pathology; D004492:Edetic Acid / Q000627:therapeutic use; D005260:Female; D005500:Follow-Up Studies; D006171:Gutta-Percha / Q000627:therapeutic use; D006801:Humans; D008297:Male; D010483:Periapical Diseases / Q000000981:diagnostic imaging / Q000628:therapy*; D010486:Periapical Tissue / Q000000981:diagnostic imaging / Q000473:pathology; D011176:Post and Core Technique; D011379:Prognosis; D011446:Prospective Studies; D011859:Radiography; D019233:Retreatment; D012387:Root Canal Filling Materials / Q000627:therapeutic use; D012388:Root Canal Irrigants / Q000627:therapeutic use; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods; D012390:Root Canal Therapy / Q000379:methods*; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D019227:Tooth Apex / Q000473:pathology; D014098:Toothache / Q000517:prevention & control; D016896:Treatment Outcome; D014945:Wound Healing / Q000502:physiology; D015035:Zinc Oxide-Eugenol Cement / Q000627:therapeutic use
chemical_list: D002614:Chelating Agents; D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants; D015035:Zinc Oxide-Eugenol Cement; D006171:Gutta-Percha; D004492:Edetic Acid; D012973:Sodium Hypochlorite; D002710:Chlorhexidine